Universal Screening for Medical Students and Doctors

What would be your ethical justification for either recommending or not recommending universal screening for all medical students and doctors?

What is the ethical rationale for allowing or not allowing medical students who are MRSA carriers to continue their medical education? How would it change your recommendation if the MRSA of this student was not PVL-positive? If was there little or no evidence that excluding colonized healthcare workers decreases risks to patients? If the students agreed to pursue medical specialties that do not involve patient care?